PineTime runs only with 3.3V via pogopin
#2
@jvw1954 I am by no means an expert with this device, I'll try to get some persons in here that are.

A few things to try:

* Try flashing a known good image before doing anything else - I can personally say that JF's latest release works well.

* Hold down the power button for a long time - many of OSes recognize this as a request for reset.

* A battery disconnect and reconnect (you might need need to de-solder the battery from the pad). It's a pain, but this will ensure the device is fully reset.

I've just checked the PineTime schematic [1] for possibilities of reasons why you wouldn't get power from the battery, but unfortunately it's not so clear. You should test the following if you have a voltmeter and post the results (with and without pogo pin power applied):

* TP21 (5V) to TP22 (GND)

* TP23 (~3.3v to ~4.2V) to TP24 (GND)

* TP25 (3.3V) to TP26 (GND)

That should tell us if you're seeing battery power and whether the regulator is working correctly. If you've got a busted regulator, I would expect to see TP25 to read 0V when measuring just the battery is connected. That would in theory explain why bypassing it would bring the CPU up.

I would suggest to the circuit designer to make some modifications:

1. A diode on pogo pin inputs to prevent somebody accidentally connecting 5V to a 3.3V line, or vice versa. We're talking a few cents to save tonnes of potential headaches.

2. Throw a diode in front of the 5V input, USB can really vary as high as 6V (and as low as 4V) if you're unlucky. Depending on U14ME6206, you could even throw the 5V USB input through the same regulator as the batter (using some diodes to block battery and 5V from one another). The regulator would then be powered from the highest voltage source, which should be USB at ~5V.

3. Use a standard connector instead of pogo pins, it's much better than some temperamental connection. I believe they do JST connectors at the right size and with a some slight layout changes there will be enough space in there (bring it out away from the side of the watch wall).

[1] https://files.pine64.org/doc/PineTime/Pi...191103.pdf


Messages In This Thread
RE: PineTime runs only with 3.3V via pogopin - by barray - 12-18-2020, 12:25 AM

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